AIRWORTHINESS DIRECTIVE
CAA-AD-026/1999
Date of issue: February 25, 1999
AIRCRAFT - INSPECTION OF THE BEARING HOUSING OF THE MAIN LANDING GEAR SUPPORT ASSEMBLY
Applicability: SAAB SF 340A -004 through -159 and SAAB 340B -160 through -444
Effective date: March 25, 1999
Compliance: Required as indicated in SAD No. 1-137.
Remarks: Where applicable, the requirements of this AD must be integrated into the Aircra
ft's Logbook(s). Address inquiries concerning this AD to: Civil Aviation Authority, Airworthiness Division, Ruzyně Airport, 160 08 Prague 6, Czech Republic, tel.: 420 2 324086, fax: 420 2 364112.Ing. Pavel MATOUŠEK
Director of Airworthiness Division, CAA CZ
LUFTFARTSVERKET Aviation Safety Department SWEDISH AIRWORTHINESS DIRECTIVES (SAD)
SAD No 1-137
Section 1. Swedish Manufactured Aeronautical Products
AIRWORTHINESS DIRECTIVE NO: 1-137
AIRCRAFT TYPE: SAAB SF 340A and SAAB 340B
SERIAL No’s AFFECTED: SAAB SF 340A -004 through -159 and SAAB 340B -160 through -444
SUBJECT: Wings - Attach fittings - Inspection of the Bearing housings of the main landing gear support assembly
BACKGROUND:
During replacement of landing gear support assembly bearings, pitting corrosion has been found in the outboard and inboard bearing housings. This is most probably caused by moisture intrusion between the bearing and bearing housing surface. These fittings are currently classified as Safe Life item and normally not considered as Fatigue Critical. Pitting corrosion may initiate fatigue cracks leading to a reduction of the fatigue life of the support assembly.
This SAD calls out an inspection of the bearing installation and gives instruction for an improved installation of the bearings and or repair/replacement of the support assembly if necessary.
Adding an entering radius on the bearing outer surface will avoid damage on the anodized surface in the bearing housings during installation. Improvement of the surface treatment in the bearing housing and sealing after the bearing installation will minimize the possibility for corrosion.
REFERENCE DOCUMENTS: Saab Aircraft AB Mandatory Service Bulletin SAAB 340-57-034 dated 28, January 1999
ACTIONS: : Perform actions described in Saab Aircraft AB Mandatory Service Bulletin SAAB 340-57-034 dated 28 January 1999 or later revision
COMPLIANCE TIME:
For A/C with 32000 accumulated flights or more, to be performed within 4000 flights from effective dated of this SAD.
For A/C with 24000 - 32000 accumulated flights, to be performed within 6000 flights from effective date of this SAD.
For A/C with less than 24000 accumulated flights, to be performed at scheduled overhauls (at 12000 or 24000 accumulated flights) of the landing gears or within 6000 flights from effective date of this SAD.
EFFECTIVE DATE: 3 February,1999